The present invention relates to an alignment device for an external coil in a transcutaneous energy transfer (TET) system.
Certain medical devices implanted within the body must be supplied with electrical power. For example, ventricular assist devices used to supplement the pumping action of the heart must be supplied with power, typically a few watts to tens of watts. This power can be supplied through a wire penetrating the skin. However, such a wire poses a risk of infection, particularly when left in place for months or years. Measures to alleviate this risk add to the burden placed upon the patient and caregivers. TET systems transmit power into the body without the use of wires penetrating the skin, and thus avoid these risks. In certain TET systems, an internal coil and an external coil are provided, the internal coil being implanted within the body of a patient. The internal and external coils include coiled conductors. An alternating current is provided to the external coil, thereby inducing an alternating magnetic field which penetrates the skin and impinges on the internal coil to induce an alternating current in the internal coil. This current may be used to power devices implanted within the body of a patient.
In such a system, the current generated in the internal coil depends directly on the alignment of the internal and external coils. Poor alignment will result in poor energy transmission from the external coil to the internal coil.